1. Field of the Invention
The present invention relates to a display panel, and more particularly, to a liquid crystal display (LCD) panel having a plurality of repair lines and signal lines disposed at different substrates.
2. Description of the Prior Art
Liquid crystal displays (LCDs) have advantages over certain other displays, including advantages of portability, low power consumption, and low radiation emissions. The LCDs have been widely used in various portable information products, such as notebooks, personal digital assistants (PDAs), video cameras, and other similar devices. Furthermore, CRT monitors are being replaced by the LCD.
A general architecture of the LCD panel includes a thin-film transistor (TFT) substrate, a color filter (CF) substrate, and a liquid crystal layer between the two substrates. The TFT substrate includes a pixel matrix composed by a plurality of data lines and a plurality of scan lines. The pixel matrix of the TFT substrate, formed by the plurality of data lines and the plurality of scan lines, includes a pixel driver IC formed by electrical components such as a TFT and a capacitor installed at each intersection of each data line and each scan line. The pixel driver IC can receive a video data signal transmitted from the data line and a switch/address signal transmitted from the scan line to control operation of the corresponding pixel. In order to prevent an open circuit in the signal transmission of the data line or the scan line, in manufacturing the LCD panel, a plurality of repair lines is usually disposed in a peripheral area of the panel so that when an open circuit occurs in the transmission of external video data signals or the switch/address signal, the signals can still be transmitted to the LCD panel via the repair line for controlling the pixel operation such that poor display quality of the LCD panel due to the open circuit of the data line or scan line can be prevented.
FIG. 1 illustrates a top view diagram of a TFT substrate of a conventional LCD panel 10. The TFT substrate of the LCD panel 10 includes a plurality of parallel data lines D1-Dm and a plurality of parallel scan lines S1-Sn disposed in a display area 20. The data lines D1-Dm and the scan lines S1-Sn are intersecting and form a pixel matrix 12. Each pixel and corresponding pixel driver IC formed by electrical components such as TFTs and capacitors is represented as a dot in FIG. 1. A source driver IC and a gate driver IC are packaged in a tape carrier package (TCP) manner and are represented as TCPs 24 and 26 of FIG. 1. The data lines D1-Dm can be coupled to a printed wiring board (PWB) 14 through the TCP 24 and can receive signals transmitted from the source driver IC, and the scan lines S1-Sn can be coupled to a PWB 16 through the TCP 26 and can receive signals transmitted from the gate driver IC. Repair lines T1-Ts of the LCD panel 10 can be disposed in an area outside of the display area 20 of the TFT substrate as a backup route for transmitting signals when an open circuit occurs in the data lines D1-Dm. Under normal circumstances, the repair lines T1-Ts and the data lines D1-Dm are not electrically connected.
FIG. 2 illustrates a resolution for a conventional LCD panel 10 when an open circuit occurs in a data line. If the open circuit occurs at a point A of the data line Dm (the open circuit is illustrated as “x” in FIG. 1), the conventional method utilizes a laser welding method to connect a point B and a point C of the data line Dm to two ends of the repair line T1. The connecting point of the data line Dm and the repair line T1 after the laser welding is illustrated as ▴ in FIG. 2, and the arrows in FIG. 2 represent the signal transmission route at this moment. The normal signal transmission route starts from point B and continues to point C of the data line Dm, however, if an open circuit occurs in the data line Dm, the signal will be transmitted from point B to point C of the data line through the repair line T1. In other words, the signal has to pass through the topside, left side, and bottom side of the display area 20 before transmission is completed. The resulting resistance value will be too high because the transmission route is too long. More specifically, a resistance: RC delay effect is easily generated with the liquid crystal layer, hence the success rate of repairing the open circuited line is reduced. Furthermore, this technique increases the power consumption of the LCD panel 10.
In the architecture of the conventional LCD panel 10, the data lines D1-Dm, the scan lines S1-Sn, and the repair lines T1-Ts are disposed on the TFT substrate. In order to avoid affecting the operation of the pixel, the repair lines T1-Ts must be disposed outside the display area 20, such that the lengths of the repair lines T1-Ts are longer than those of the data lines D1-Dm, making the transmission route provided by the repair lines T1-Ts too long, the resistance value too high, and the RC delay effect too easily generated with the liquid crystal layer, hence the success rate of repairing the open circuited line is lowered and the power consumption of the LCD panel 10 is increased. Furthermore, after the components, such as the data lines, the scan lines, and the driver ICs, are disposed on the TFT substrate, there is limited space left to dispose the repair lines. Therefore, the conventional LCD panel 10 can only provide a limited amount of space for repair lines and the repair capability is insufficient.